The Last of the Spare Tires

Ever since the first mass-produced Ford Model T rolled off the production line, automakers around the world have grappled with the challenge of reducing overall weight. An average 16-inch car tire weighs about 10 kilograms, with the rims adding another 10 kilograms in additional weight. While a spare tire is greatly convenient, it represents a significant dead weight that affects fuel efficiency. Improving tire performance and innovations in tire technology are other factors that have led to the inevitable step of car manufacturers entirely removing the spare tire from their newer releases.

Tire Inflation Kits

As a consequence, spare tires are being replaced with tire inflation kits that include a manual or electric pump, tire patches and a high-density sealant. These kits are ideal for DIY drivers who do not struggle with a flat and can temporarily patch the tire. Continental’s Conti Mobility Kit includes a compressor that makes the overall weight of the kit just a little over 1 kilogram and allows a user to inject a foam-based sealant to repair the puncture. The company reports a success rate of 80 percent and an effective running period of over 640 kilometers.

Space Saver Tires

Space saver spare tires are the other popular option to a full-weight tire. Australian manufacturers were the pioneers of the space saver wheel, introducing a wheel that featured a smaller rim and thinner tires that spread to Europe and subsequently, to a global consumer base. Over 30 years since their introduction, these emergency tires are making a comeback as a feature in city-driven cars. These alternatives serve as a suitable replacement for short distances until the punctured tire can be repaired. Longevity and traction are two factors that make space-saving spares a temporary fix. The technology has polarized the automotive community, with several automotive societies and auto advocacy organizations supporting the use of space-saving spares for their convenience and long-terms savings to manufacturers and consumers while other organizations oppose the use of the tires citing concerns about safety and the restrictions placed on driving.

Typically, space saver or temporary tires limit the speed of your car and are not advised in situations that involve heavy braking and cornering. Structurally, a space saver tire has a much lower ply rating than a standard tire. This rating is an indication of the tire’s ability to handle inflation and loads. Consequently, it is vitally important that users who are considering a replacement for a standard spare tire to ensure that the lighter, less durable space saver tires are able to take the fully laden weight of the car. Manufacturer-provided space savers are about 7 kilograms lighter than normal tires, easier to handle, and meet strength and driving test specifications. Despite the limitations, space saver tires offer significant improvements in boot space and fuel economy.

‘Healing’ and ‘Run-Flat’ Tires: Alternatives to the spare tire

Self-sealing or ‘healing’ tires are based on another technology that is making a comeback. Designed by German-headquartered tire giant Continental, self-sealing tires employ an air-proof insulated layer that prevents air from escaping. Research by the company has revealed that most puncture-causing objects are in the 3mm to 5mm dimension range, and tailoring tires to respond to that range is an option that has been migrated to other automakers. Conversely, ‘Run-Flat’ tires use a reinforced sidewall that prevents the rims from grinding into the asphalt when the tire is punctured. While ‘healing’ tires offer the advantages of lower weight, ‘run-flats’ prevent any damage to the rims, even in the case of a large-object puncture, thereby, eliminating the need for a spare wheel.